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西安法华寺黄土崩塌形成—运动机理研究

发布时间:2018-11-19 17:32
【摘要】:黄土崩塌的危害是众所周知的,但有效防治一直是非常棘手的,这里面的关键瓶颈就是其机理问题。为了探索解决这一问题,拟结合西安法华寺黄土崩塌灾害实例进行灾害孕育、发展、变形、破坏全过程研究,定量讨论黄土崩塌灾害形成-运动机理,为黄土崩塌灾害防治服务,主要得到以下四点研究成果:(1)针对法华寺黄土崩塌,提出了影响法华寺黄土崩塌的内因及外因。内因包含坡体形态、坡体结构、植被作用;外因包含降雨作用、地震作用、工程活动,为法华寺黄土崩塌机理研究奠定基础。(2)针对法华寺黄土崩塌,提出了三种形成机理。①暴雨状态崩塌形成机理:雨水入渗、富集-裂隙扩张、充水-破裂面浸润、破裂面贯通-崩塌发生。②地震状态崩塌形成机理:地震力作用-土体剪断解体-获得初速度-产生运移-崩塌发生。③工程活动状态崩塌形成机理:工程活动作用-破坏应力平衡-降雨或振动作用-破裂面贯通-崩塌发生。(3)提出了法华寺黄土崩塌“变形-倾倒-坠落-堆积”的运动机理。阐释了各阶段崩塌体特征。①后缘裂隙变形阶段:在重力、顶部建筑物及其他外力作用下,坡顶面出现不均匀沉降,产生拉张裂隙。②倾倒阶段:当裂隙充水时,静水压力迅增导致下滑力矩骤增,崩塌体在破裂面底端发生倾倒运动。③坠落阶段:崩塌体重心移出斜坡之后,脱离母体向下坠落,其过程为斜下抛运动。④堆积阶段:崩塌体经坠落后,撞击地面产生危害。并建立了各阶段运动方程。(4)基于法华寺黄土崩塌灾害的运动过程认识,建立崩塌体地质模型,借助离散元程序对崩塌体“变形-倾倒-坠落-堆积”的全过程进行数值模拟,确定暴雨状态、暴雨+地震状态崩塌体影响范围模拟值,通过对比发现,暴雨+地震状态崩塌体的影响范围模拟值与影响范围理论值、实际值较为接近。
[Abstract]:The harm of loess collapse is well known, but effective prevention and cure is always very difficult, the key bottleneck is its mechanism. In order to solve this problem, it is proposed to study the whole process of disaster inoculation, development, deformation and destruction, and discuss quantitatively the formation-movement mechanism of loess collapse disaster. For the prevention and control of loess collapse, the following four main research results are obtained: (1) aiming at the loess collapse in Fahusi, the internal and external factors affecting the collapse are put forward. Internal causes include slope shape, slope structure and vegetation. The external causes include rainfall action, earthquake action and engineering activities, which lay a foundation for the study of the collapse mechanism of the Loess in the Fahua Temple. (2) three kinds of formation mechanisms are put forward for the collapse of the Loess in Fahashi. 1 the formation mechanism of collapse in the rainstorm state: Rain Water infiltration, Enrichment-fracture expansion, water filling-fracture surface infiltration, 2 formation mechanism of earthquake state collapse: seismic force action-soil shear disintegration-obtaining initial velocity-generating migration-occurrence of collapse. 3 formation mechanism of engineering active state collapse: engineering activity Action-failure stress balance-rainfall or vibration-fracture surface transfixion-collapse. (3) the movement mechanism of "deformation-toppling-falling-stacking" of Loess collapse in Fahua Temple is put forward. The characteristics of collapse body in each stage are explained. 1 the deformation stage of fracture in the rear edge: under the action of gravity, top building and other external forces, uneven settlement occurs on the top of the slope, resulting in tensile fissure. 2 the collapse stage: when the crack is filled with water, The rapid increase of hydrostatic pressure results in a sharp increase in the sliding torque, and the collapse body collapses at the bottom of the fracture surface. 3 falling stage: after the collapse body center of gravity is moved out of the slope, the collapse body falls down from the parent body. The process is oblique throwing movement. 4 stacking stage: after falling, the collapse will cause harm to the ground. The equations of motion of each stage are established. (4) based on the understanding of the movement process of the loess collapse disaster in Fahusi, the geological model of the collapse body is established. With the help of discrete element program, the whole process of deformation, toppling, falling and accumulation of collapse body is numerically simulated, and the simulation value of the influence range of collapse body in heavy rain state and storm earthquake state is determined. The simulated values of the influence range of the collapses in the torrential rain state are close to the theoretical values of the influence range, and the actual values are close to those of the theoretical values.
【学位授予单位】:西安科技大学
【学位级别】:硕士
【学位授予年份】:2017
【分类号】:P642.21

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